Not a Mountain

Riddle
Riddles are little poems or phrases that pose a question that needs answering. Riddles frequently rhyme, but this is not a requirement.

I tower over the man-made plain;
My peaks scrape the heavens.
I have many brothers; in fact,
We may be as many as a hundred and seven.

We're as ancient as the oldest trees,
But not older than the hills.
We've been studied for centuries now,
But with mystery we're still filled.

Hint

The greatest of us is great indeed,
He's ranked a man-made Wonder.
We think his hat of gold was stolen
By a desecrating robber.

Answer

The pyramids of Egypt.

It's estimated that there are 80-110 pyramids in Egypt, the oldest of which are around 4,500 years old. (The oldest living tree is about 4,750 years old.) Scholars have been studying the pyramids for nearly 200 years, but there are still many questions about them. We don't even know how they were built!

The Great Pyramid at Giza is one of the Seven Wonders of the World. Some believe that it originally had a golden top that was stolen by tomb raiders.

I got it, but I must quibble. 1) At latest count there are 138 Egyptian pyramids, not 107. 2) With the tallest pyramid having reached a height of only 482 feet or so, the peaks of these constructions could hardly be said to have "scraped the heavens," in my estimation, though in all fairness I must point out that usually buildings taller than 100 meters (about 328 ft., or roughly 33 stories) do get called "skyscrapers."

Though i got the answer straight away, I too must quibble (though as the author has not been on in over 2 years it is pointless). The line "as ancient as the oldest trees" - while it is pointed out in the answer the pyramids are older than the oldest "living tree" there is no stipulation in the teaser itself we are discussing LIVING trees. Trees have been around since the world began.